Re: [Qemu-devel] memtest 4.20+ does not work with -cpu host

[Gleb Natapov]

On Thu, Sep 13, 2012 at 02:05:23PM +0200, Peter Lieven wrote:
> On 13.09.2012 10:05, Gleb Natapov wrote:
> >On Thu, Sep 13, 2012 at 10:00:26AM +0200, Paolo Bonzini wrote:
> >>Il 13/09/2012 09:57, Gleb Natapov ha scritto:
> >>>>>>>#rdmsr -0 0x194
> >>>>>>>0000000000011100
> >>>>>>>#rdmsr -0 0xce
> >>>>>>>00000c0004011103
> >>>>>Yes, that can help implementing it in KVM.  But without a spec to
> >>>>>understand what the bits actually mean, it's just as risky...
> >>>>>
> >>>>>Peter, do you have any idea where to get the spec of the memory
> >>>>>controller MSRs in Nehalem and newer processors?  Apparently, memtest is
> >>>>>using them (and in particular 0x194) to find the speed of the FSB, or
> >>>>>something like that.
> >>>>>
> >>>Why would anyone will want to run memtest in a vm? May be just add those
> >>>MSRs to ignore list and that's it.
> >>>From the output it looks like it's basically a list of bits.  Returning
> >>something sensible is better, same as for the speed scaling MSRs.
> >>
> >Everything is list of bits in computers :) At least 0xce is documented in  
> >SDM.
> >It cannot be implemented in a migration safe manner.
> What do you suggest just say memtest does not work?
Why do you want to run it in a guest? 

> I am wondering why it is working with -cpu qemu64.
> 
Because memtest has different code for different cpu models.

--
                        Gleb.